Cold email is a hit and miss approach. Just go talk to people face to face. Initially it seems like a non-scalable approach but it works wonders. The silicon valley, VC preached mantra of hyper scale is what muddles the minds of most entrepreneurs. Everyone starts thinking of million of users rather than 100s of users. There is a very interesting presentation from YC startup school 2008: https://www.youtube.com/watch?v=0CDXJ6bMkMY

You will recognise the speaker :)

I consider "just talk to people" to be in the "connections" category

Doesn't have to be. You can form connection with people who you don't know. But first you have to talk to them.